Malaysia straddles Southeast Asia's key geopolitical divide, between the mainland and the archipelago. Peninsular Malaysia occupies the southernmost tip of Southeast Asia's Malay Peninsula. East Malaysia, however, is on the island of Borneo, over 600 kilometers away across the South China Sea. Peninsular Malaysia is defined by north-south mountain ranges flanked by coastal lowlands. The nation's core is its west coast from Penang to Johor Bahru, including the capital, Kuala Lumpur. This coastline fronts major east-west trade routes through the Malacca Strait, whose shores are divided between Malaysia, Indonesia and Singapore. Malaysia's primary geographic challenge is to secure this coastline in order to extract revenue from east-west trade. Today, Malaysia's substantial manufacturing center is concentrated in this core region. Johor Bahru also benefits from proximity to Singapore, which left Malaysia in 1965. Malaysia's ethnic minority Indian and Chinese communities are also concentrated in the core, comprising 30 percent of the population. These groups wield outsized economic power and form the basis of the political opposition. Their population growth is slower than the ethnic Malay majority, creating an increasingly volatile political environment. East Malaysia makes up 60 percent of the country’s landmass but has only 20 percent of the population. This sparse population is tipped toward the ethnic Malays and is growing in electoral significance. East Malaysia is playing a growing role in energy production — key to sustaining the country’s decades of steady economic growth. Borneo also fronts the South China Sea, where Malaysia's maritime claims overlap with the claims of the Philippines, Brunei, Vietnam and China. As Borneo's offshore fields become more important to Malaysia, the nation's South China Sea claims could bring it into conflict.